1. Field of Use
This invention relates generally to a re-usable two-piece blind fastener for securing panels together and comprising a hollow plastic expandable/contractable body and a screw insertable into and removable from said body. In particular, it relates to improved thread engaging means in the body and to improved sealing means on the body or on the screw or on both.
2. Description of the Prior Art
Some two-piece blind fasteners are usable to secure a plurality of panels together in face-to-face confronting relationship. Some blind fasteners are of the expansion rivet type which cannot be removed after installation in the panel holes without being destroyed. Other blind fasteners comprise a hollow expandable body and a screw. Typically, in the screw-type fasteners the body has a body head and an expandable body shank with a threaded bore and the screw has a screw head and threaded shank rotatably insertable into the body bore to effect body shank expansion. Two basic panel arrangements are possible with such a fastener. For example, in one arrangement two or more panels may be stacked together and the body shank is inserted into aligned panel holes from one side of the panel assembly. Rotatable insertion of the screw into the body bore from the same side of the panel assembly effects body expansion and the panels are entrapped between the body head and the expanded body shank. In another arrangement, the body shank may be inserted through aligned holes in a first panel assembly (one or more panels) as aforedescribed and the screw shank may be inserted through aligned holes in a second panel assembly (one or more panels) to entrap the second panel assembly between the screw head and body head.
If the body is made of metal or of certain types of plastic, it is not possible to remove the body from the panel assembly aperture, even after the screw is removed, because the body remains in permanently expanded condition. Furthermore, few prior art fasteners of this type make provision for sealing the panel apertures or the body bore when the fastener is installed. Therefore, it is desirable to provide improved reusable two-piece blind fasteners for use with panels and panel assemblies.